Speaking about the departure, Chelsea boss Jose Mourinho told the club's official website: "To show Michael respect is to not stop him going. We would have been happy had he stayed because he is fantastic player for the team, but he's given everything for the club and a great chance arrived for his future.

"I know he can continue to play at a high level and I wish him success and happiness in Italy and at the World Cup in Brazil."

The completion of the deal will come as a relief to Milan general manager Adriano Galliani, who had sanctioned Antonio Nocerino's loan to West Ham and would have found the club short on midfielders had the move fallen through.

On Friday, Essien said he was excited about the prospect of working under new Milan coach Clarence Seedorf.

"Milan are a great club," he said. "I've joined the Rossoneri after having spoken to Seedorf. I hope he becomes a great coach."

He also expressed his gratitude to Chelsea for not standing in the way of the move, telling Milan Channel: "I would like to thank the [Chelsea] president and team and also [manager Jose] Mourinho, who has allowed me to wear this red and black shirt. I will do my best for Milan."

Mourinho confirmed earlier on Friday that the decision on whether to stay or go would rest solely with Essien, telling a news conference: "If he stays we're more than happy he stays - he is a fantastic club man and a fantastic team player.

"But he's another player who gave everything to this club and, if a great situation for him arrives, he's another one we feel we must show respect and not stop him going."

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After enduring a tricky start to his Manchester United career, perhaps it is fair that Marcos Rojo celebrated so boisterously as he watched his first professional club Estudiantes beat fierce rivals Gimnasia